Ideal fault codes, explained.
Find your code below — each guide covers what it means, likely causes, safe checks, and when to call a Gas Safe engineer.
Most searched Ideal codes
The codes Ideal owners look up most — each guide explains what the display is telling you, how serious it is, and the safe checks worth trying before you ring us.
Ideal code library (43)
C0 Ideal Fault Code C0: Causes & Solutions C2 Ideal Fault Code C2: Causes & Solutions F1 Ideal Fault Code F1: Causes & Solutions F2 FN LN Ideal Fault Code F2 / FN / LN: Causes & Solutions F3 Ideal Fault Code F3: Causes & Solutions F4 L4 Ideal Fault Code F4 / L4: Causes & Solutions F5 L5 Ideal Fault Code F5 / L5: Causes & Solutions F6 Ideal Fault Code F6: Causes & Solutions F7 Ideal Fault Code F7: Causes & Solutions F8 L8 Ideal Fault Code F8 / L8: Causes & Solutions F9 L9 Ideal Fault Code F9 / L9: Causes & Solutions FA Ideal Fault Code FA: Causes & Solutions FAN FAULT Ideal Fault Code Fan fault: Causes & Solutions FD Ideal Fault Code FD: Causes & Solutions FLAME LOSS Ideal Fault Code Flame loss: Causes & Solutions FLAME ON BEFORE GAS ON Ideal Fault Code Flame on before gas on: Causes & Solutions FLAME ON BEFORE GAS VALVE Ideal Fault Code Flame on before gas valve: Causes & Solutions FLOW TEMP CANNOT REACH 80C Ideal Fault Code Flow temp cannot reach 80°C: Causes & Solutions FLOW THERMISTOR FAULT Ideal Fault Code Flow thermistor fault: Causes & Solutions FLOW RETURN REVERSED Ideal Fault Code Flow/Return reversed: Causes & Solutions FU Ideal Fault Code FU: Causes & Solutions IGNITION LOCKOUT Ideal Fault Code Ignition lockout: Causes & Solutions L1 Ideal Fault Code L1: Causes & Solutions L2 Ideal Fault Code L2: Causes & Solutions L4 F4 Ideal Fault Code L4 / F4: Causes & Solutions L5 F5 Ideal Fault Code L5 / F5: Causes & Solutions L6 Ideal Fault Code L6: Causes & Solutions LC Ideal Fault Code LC: Causes & Solutions LOW MAINS VOLTAGE Ideal Fault Code Low mains voltage: Causes & Solutions LOW WATER PRESSURE Ideal Fault Code Low water pressure: Causes & Solutions NO CH BUT DHW WORKING Ideal Fault Code No CH but DHW working: Causes & Solutions NO DHW BUT CH WORKING Ideal Fault Code No DHW but CH working: Causes & Solutions NO WATER FLOW FAULT Ideal Fault Code No water flow fault: Causes & Solutions OUTSIDE SENSOR FAULT Ideal Fault Code Outside sensor fault: Causes & Solutions OVERHEAT LOCKOUT Ideal Fault Code Overheat lockout: Causes & Solutions PCB ERROR Ideal Fault Code PCB error: Causes & Solutions PCB RECENTLY REPLACED Ideal Fault Code PCB recently replaced: Causes & Solutions PUMP ROTOR BLOCKED Ideal Fault Code Pump rotor blocked: Causes & Solutions RETURN THERMISTOR FAULT Ideal Fault Code Return thermistor fault: Causes & Solutions THERMAL FUSE LOCKOUT Ideal Fault Code Thermal fuse lockout: Causes & Solutions TOO MANY RESETS Ideal Fault Code Too many resets: Causes & Solutions TOO MANY RESTARTS Ideal Fault Code Too many restarts: Causes & Solutions WATER PRESSURE Ideal Fault Code Water pressure: Causes & Solutions
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